A damper device is installed in the flow passage of cold air to control the flow of the cold air in a refrigerator. An example of a conventional damper device 100 includes, as shown in FIG. 13, a drive part 101, a baffle 102 driven by the drive part 101, and a frame 104 forming an aperture part 103 which is opened or closed by the baffle 102 (see Japanese Patent Laid-Open No. Hei 09-264652).
The frame 104 and the baffle 102 are installed on the way of the flow passage of cold air from an evaporator to a refrigerating compartment to control the flow of the cold air by opening and closing the baffle 102. In other words, in the flow passages 105, 106 sandwiching the frame 104 and the baffle 102 between them, the flow passage 105 is in communication with the evaporator and the flow passage 106 is in communication with the refrigerating compartment.
The drive part 101 is disposed outside of the flow passages 105, 106. The drive part 101 includes a rotation shaft 108 connected to a shaft part 107 of the baffle 102 to turn the baffle 102, and a motor and a deceleration gear train for turning the rotation shaft 108. The motor and the deceleration gear train are built within a case 109 and a lid 110 of the drive part 101. The joint part 111 of the lid 110 and the case 109 is directly exposed to the cold air. The joint part of the case 109 and the draw-out port of a connector or a vinyl wire is also directly exposed to the cold air.
Since the flow passage 105 of the damper device 100 is in communication with the evaporator and the flow passage 106 is in communication with the refrigerating compartment, a temperature difference may occur around the damper device 100 and frost is easily formed on it. When the frost melts, moisture adheres on the periphery of the damper device 100.
However, in the damper device 100 described above, since the joint part 111 of the drive part 101 is exposed, the frost may melt and moisture enters into the inside of the drive part 101 from the joint part 111. When the moisture enters into the drive part 101, the moisture may freeze in the drive part 101 again which causes the gears to be locked because the frozen moisture is caught between the gears. Alternatively, the moisture may cause the metal disposed inside of the drive part 101 to rust, which may also result in the gears to be locked.